1. Field of the Invention
The present invention relates to loading mechanisms for truck trailers onto railroad cars, and more particularly to side loading mechanisms for lifting trailers along the side of the railroad track.
2. Description of the Prior Art
The economies of shipping truck trailers on railroad cars are well recognized. In consequence, those engaged in the transportation of goods often resort to "intermodal" shipping, in which a variety of shipping methods is utilized. Since a large component of all freight ends up on the water a certain amount of standardization has occurred. Thus, the truck trailer now takes one of the forms necessary for handling a standardized container.
We note, with some emphasis, that these standardized trailer dimensions are particularly useful in the transfer between the highway and rail transportation modes. Thus, any exchange between railcar and truck is best effected by a transfer of a trailer with the container mounted thereon.
In consequence, those techniques earlier devised for manipulation of containers, alone, are often unsuitable for the transfer of the supporting trailer. Thus, the teachings of U.S. Pat. No. 4,124,129 to Barry; U.S. Pat. No. 4,130,208 to Barry; U.S. Pat. No. 4,715,766 to Gebhardt; U.S. Pat. No. 4,093,084 to Ringer and U.S. Pat. No. 4,139,107 to Ninomia et al; while suitable for the purposes intended, each accommodate the transfer of the container only. U.S. Pat. No. 4,746,257 to Barry, and U.S. Pat. No. 4,747,745 to Pippen et al, in turn, rely on complex pivotal mechanisms or overhead cranes to effect the transfer of the trailer itself.
The complexity and cost of overhead cranes, or raised loading platforms from which the trailer is pivoted, dictate fixed loading and unloading points along the rail line. This limiting aspect of large, fixed capital intensive loading facilities then limits the number of loading stations along the track. In consequence, full intermodal utility is often not realized because of the fixed character of the capital investment.
As result, techniques have been devised in the past which, on one way or another, effect loading transfer onto a rail line without extensive fixed capital equipment. One example thereof is described in U.S. Pat. No. 2,773,612 to West et al. While suitable for the purposes intended the structure of the '612 patent may be further improved, both for manipulative convenience and for structural efficacy. Such improvements are extensively sought and it is one such improvement that is disclosed herein.